May the Kush and cookies be with you!

Yes, last stage of P deficiency Also problem with Ca

Overwatering is causing the nutrient issue. The claws are a sign of to much nitrogen but with the leaves being light colored, I'm assuming you're over watering and the nutrients are leaching

Good Evening Mr.HH From the pictures and your description, it doesn’t look like a classic phosphorus deficiency. With phosphorus issues, leaves usually turn dark, sometimes with a purple or bluish tint, and necrotic spots spread from the edges inward. In your case, the damage looks more like a mix of nutrient imbalance (possibly potassium deficiency or pH-related lockout) and some light stress, since you mentioned many leaves are pointing upwards. I’d recommend Check your pH of both the nutrient solution and runoff often deficiencies are not from lack of nutrients, but from pH blocking their uptake. Check potassium (K) levels burned edges and spotting often point to K deficiency rather than phosphorus. Review watering routine irregular watering can worsen nutrient uptake. Light height even at 50%, make sure your Spider Farmer isn’t too close. Leaves pointing straight up can mean they’re reaching for light or reacting to too much intensity. In short: before adding extra phosphorus, double check pH and overall feeding plan. Often it’s not about “more nutrients” but correcting balance and uptake

The leaf damage looks more like potassium deficiency (K) than phosphorus or calcium the rusty, burned edges are typical for K issues. Phosphorus usually shows darker/purplish tones, and calcium more spotty necrosis. With pH at 6.7 you’re on the upper end, so nutrient uptake might already be limited. Personally, I always keep it around 6.0–6.3 max for better balance. Since K, Ca, and Mg are often hard to tell apart and interact with each other, I’d supply all three components together instead of guessing just one. No need to flush unless you’ve overfed better to adjust feedings and ensure a steady base instead of only using Big Bud

Looks more like a root zone / irragation issue. Waiting for a proper dryback is good, but are you fully saturating the medium? If you are choosing a volume to give and not giving what is needed to fully saturate, that's likely theproblem. i would not do a 'flush' but maybe get a little extra runoff for an irriation or 2. Feed as you normally would. you amened some peat moss, so how you fertilize is a supplementation of what remains in the soil... like riding a bike, you have to figure that out on your own. The plants don't look lush, so i doubt you are over-feeding. i would not reduce feed but if symptoms continue, change formula of feed for sure. again, i think this is more about the root zone. the damage is all around the veins to start. Check any marijuana leaf symptom chart and you'll see this is difficult to match up to anything... the location and progression don't match. the plant doesn't look overly lush and you say the pH is balanced (6.7 is fine for soil).

actually P def is already fixed, new growth is fine but Ca def still there